1. Field of the Invention
The present invention relates to an IC socket used for testing of various IC packages, such as QFP (Quad Flat Package), SOP (Small Outline Package) and so forth.
Typically, IC packages are tested in some manner to ensure their proper functions. The present invention relates to the IC socket which enables various tests for a plurality of IC packages quickly and certainly.
2. Description of the Prior Art
One of the tests for IC packages is the burn-in test, in which the IC package is inserted into the IC socket and thereafter installed within a convection oven for testing high-temperature characteristics of the IC package under elevated temperature.
IC sockets used for the above-mentioned burn-in test are known and some are adapted for testing using automatic equipment. For example, U.S. Pat. Nos. 4,623,208 and 4,886,470 disclose IC sockets adapted to automated-type testing apparatus.
FIG. 6 shows the conventional IC socket disclosed in U.S. Pat. No. 4,623,208. In further detail, FIG. 6 is a perspective view showing a normal condition before testing, FIG. 7 is an exploded perspective view showing overall construction, FIG. 8 is a section of the condition, in which the IC package is inserted, as taken along line A--A of FIG. 6, and FIG. 9 is a section of the condition, in which the IC package is installed, as taken along line A--A of FIG. 6.
FIGS. 10 to 12 show the conventional IC socket disclosed in U.S. Pat. No. 4,886,470. In further detail, FIG. 10 is a perspective view in the normal state before testing, FIG. 11 is a section of the condition, in which a lead of the IC package is contacting the contact, as taken along line B--B of FIG. 10, and FIG. 12 is a section of the condition, in which a lead of the IC package is held in non-contact with the contact, as taken along line B--B of FIG. 10.
As illustrated, the above-mentioned two kinds of IC sockets comprise socket bodies 10, covers 20 and a plurality of contacts 30. Each of the contacts 30 has a contact section 40 for electrical contact with the lead L of the IC package P (strictly speaking, a pad of a chip carrier corresponds to the lead in the first prior art example FIGS. 6 to 9), a cantilever section 50 for rotating the contact section 40 to enable connection and releasing between the lead L and each contact 30.
Here, when the cover 20 is depressed downwardly against a resilient force (reacting force) of the contact 30, the above-mentioned contact 30 is forcingly displaced outwardly to place the contact 30 and the lead L of the IC package P into the non-contacting state to release connection therebetween. Accordingly, in this condition, insertion and removal (loading and unloading) of the IC package P can be performed. When the depression force on the cover 20 is removed, the contact 20 is rotated in the reverse direction to restore connection with the lead L of the IC package P.
However, in the above-mentioned IC socket, when the cover 20 is operated for testing the IC package, if the depression force on the cover 20 is offset, the cover 20 may move downwardly in a tilting position. AS a result, sufficient rotation cannot be obtained at the contact, on which the depression force is insufficient, and problems can arise in insertion and removal of the IC package.
In order to solve this problem, there has been proposed an IC socket which can prevent the cover 2 from tilting upon operation by providing guide posts or so forth at four corners of a socket body 1 and the cover 2. However, in case of this IC socket, the four corners of the socket 1 and the cover 2 cannot be for other uses, such as screw holes for fixing the socket body, or holes for the positioning of an automatic loader.
The present invention is established in view of the above-mentioned problems. It is an object of the present invention to provide an IC socket which can prevent a cover from tilting during operation without providing guide posts or so forth at four corners of the socket body and the cover.